Noob RAW question..

[dip_gohil]

As a noob to all of this, am I correct in assuming that a RAW image is

essentially a 'digital negative' of a digital photograph as compared to a jpeg,

which is a digital photograph that has been subjected to image processing by

the camera's own settings?

 

With this assumption in mind, would it be feasable for me to get an

acceptable/good/correct exposure if I shot in RAW by post processing with the

RAW software if my photographs were deliberatly underexposed?

 

By deliberatly underexpose my RAW photographs I could get a faster shutter

speed/ not use high ISO which causes grain etc or go tripod-free in low light

situations, then perhaps adjust the 'ev' values in the RAW imaging software in

the hope that it might spit back a decent exposure? At the moment, I am camera-

less, my kid brother has taken my 400d to Rome so I can't expiremnt

 

If this is possible, i might be tempted to be more ambitious with my low light

photography!

Cheers..

[don_e]

I underexpose, for a different reason, and recover the shadows in the raw conversion. There's limits, of course.

 

I don't think of a raw data file as a digital negative, but as the exposed but undeveloped film. Unlike film, the development process is non-destructive.

[tom_swanson]

Underexposure is a great way to get noise in your images. Far more noise in the shadows. Tends to be pattern noise for me and that is a pain to deal with. Shoot at a reasonable ISO if you can.

 

At the same time I shot this at iso 3200 -2 EV and hammered it with neat image. Worked for this subject matter. Might not for others.<div></div>

[ronaldo_r]

No, it's not going to be be "feasible". RAW is not going to help with stuffed up exposures, it's an urban myth.

[ronald_moravec1]

No, you need to get the entire histogram inside the boundries, raw or jpeg, for best results.

[gary_lester1]

Hi,

I don't know whether assumptions combined with low ISO and high shutter speeds might

make it feasable for RAW imaging software to spit back a decent image captured in low light.

But I can tell you that Image Overlay is one technique that often will improve dark images

and help cancel color noise.

Good luck!

[bernardwest]

Hi dib. I don't know what camera you shoot with, but with my Canon the H ISO setting (3200) is implemented just like you describe. It is ISO 1600 pushed to 3200 by underexposing at capture and boosting exposure via software in-camera. The problem is that by underexposing you will lose dynamic range (ie. you will clip the shadows) and when exposure is boosted you will also boost noise. If you took two photos, one at 400 ISO pushed to 800, and one at 800 ISO in camera, the image pushed to 800 would display more noise than the one captured at 800 ISO as the signal to noise ratio is less (worse) in the pushed image.

[eleary]

I'm a newbie too and find that pushing iso some to get more shutter speed is the way to go...the more data I start with the better chances of fixing in RAW

[steven_clark]

Amplifying the signal digitally by bumping up the brightness in post process isn't going to give you any less noise than amplifying it in analog by changing the ISO setting, in fact it might give you more. There is no free ride here in the real world.

[tom_swanson]

No, but you can get a viable image. With reduced dynamic range of course.

[arash khoshghadam]

sometimes, the real nature of the RAW is hidden behind a load of what has been said about this file format. he truth is that RAW files come directly from the image sensor which is a 12-bit device (X3) with a very

wide dynamic range and more flexibility. There is no such thing in RAW world as interpolation, so you get everything in real, but the moment you start to manipulate the image, tweaking the exposure and the stuff is the time you have started to change the codes and interpolation. An overexposed or underexposed RAW file has better chance of survival since it is processed in your computer,using a faster and more sophisticated CPU than that of the camera and more marked flexibility, but the noise is there specially in the shadows and if you tweak excessively you get banding in the evenly-colored or blank space. higher ISO as some friends here have suggested is way better since there is no need to tweak everything. your only concern will be to eliminate the noise which can be done in excellent softwares such as Noise Ninja ( if you master it of course )

[johnclinch]

One of the best bits of advice I've ever had is that for low light you are better off with high iso and the correct exposure, than a lower iso and the wrong exposure. It is also true that hi iso is better than too slow a shutter speed.

 

My camera is a D70s, no hi iso demon but 1600 iso images run through Capture one le are fine, if the initial exposure was correct.

 

This is a iso 1600 panorama in a once in a life time situation. I am glad I didn't try 400, although I did use 1000 on some.

 

http://farm1.static.flickr.com/237/460158359_c925800587_b.jpg

[k_stanulis]

I'm a noob too. And in response to the last post, what would have happened if you used ISO 400 in that situation?

 

Cheers

[johnclinch]

sorry for not responding before

 

Ok if I'd used iso 400 either I would have had the correct exposure and camera shake, wrecking the photo. This is the worst option by far, once its blurred its blurred

 

Or it would be very under exposed. Dealing with the under exposure makes more noise than using iso 1600